Dell S4048T, Configuration Manual

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Enabling Additional Paths
The add-path feature is disabled by default.
NOTE: Dell Networking OS recommends not using multipath and add path simultaneously in a route
reflector.
To allow multiple paths sent to peers, use the following commands.
1 Allow the advertisement of multiple paths for the same address prefix without the new paths replacing
any previous ones.
CONFIG-ROUTER-BGP mode
bgp add-path [both|received|send] path-count count
The range is from 2 to 64.
2 Allow the specified neighbor/peer group to send/ receive multiple path advertisements.
CONFIG-ROUTER-BGP mode
neighbor add-path
NOTE: The
path-count
parameter controls the number of paths that are advertised, not the number of
paths that are received.
Configuring IP Community Lists
Within Dell Networking OS, you have multiple methods of manipulating routing attributes.
One attribute you can manipulate is the COMMUNITY attribute. This attribute is an optional attribute that is
defined for a group of destinations. In Dell Networking OS, you can assign a COMMUNITY attribute to BGP
routers by using an IP community list. After you create an IP community list, you can apply routing decisions
to all routers meeting the criteria in the IP community list.
IETF RFC 1997 defines the COMMUNITY attribute and the predefined communities of INTERNET,
NO_EXPORT_SUBCONFED, NO_ADVERTISE, and NO_EXPORT. All BGP routes belong to the INTERNET
community. In the RFC, the other communities are defined as follows:
• All routes with the NO_EXPORT_SUBCONFED (0xFFFFFF03) community attribute are not sent to
CONFED-EBGP or EBGP peers, but are sent to IBGP peers within CONFED-SUB-AS.
• All routes with the NO_ADVERTISE (0xFFFFFF02) community attribute must not be advertised.
• All routes with the NO_EXPORT (0xFFFFFF01) community attribute must not be advertised outside a
BGP confederation boundary, but are sent to CONFED-EBGP and IBGP peers.
Dell Networking OS also supports BGP Extended Communities as described in RFC 4360 — BGP Extended
Communities Attribute.
To configure an IP community list, use these commands.
1 Create a community list and enter COMMUNITY-LIST mode.
CONFIGURATION mode
Border Gateway Protocol IPv4 (BGPv4) 245